In the application of a film having repellency to water and oil, e.g., window glass of automobiles and buildings, abrasion resistance of the film is required in addition to water-repellant and oil-repellant functions.
For example, in Patent Document 1 is disclosed a water-repellant and oil-repellant antifouling glass plate on which a film containing a long chain substance having a carbon fluoride group and a hydrocarbon group as major components, a short chain substance having a carbon fluoride group, a hydrocarbon group, and a silyl group as major components, and a substance having a siloxane group as a major component has been formed. Patent Document 2 discloses a water-repellant and water-separate antifouling treating solution comprising a substance 1 having at least a carbon fluoride group as a major component, a substance 2 having a hydrocarbon group as a major component, and a solvent. Moreover, Patent Document 3 discloses a solution for forming a water-repellant and oil-repellant antifouling composite film that is a solution prepared by diluting, with an organic solvent, a first substance containing a carbon fluoride group containing at least an organic fluorine-containing ether group or an organic fluorine-containing polyether group, a hydrocarbon group, and an alkoxysilyl group, a second substance containing a carbon fluoride group, a hydrocarbon group, and an alkoxysilyl group and differing from the first substance, a third substance represented by (AO)3Si(OSi(OA)2)pOA, wherein p can be 0 or an integer, A can be an alkyl group, OA can be Cl or NCO, and a silanol condensation catalyst, wherein the molecular length of the second substance is shorter than the molecular length of the first substance.
Patent Documents 1 to 3 disclose examples in which a solution for forming a composite film is prepared by dissolving a long chain substance and a short chain substance, e.g. CF3—(CF2)7—(CH2)2—Si(OCH3)3, in a prescribed solvent, and then a glass plate is dipped in this solution to form a composite film on the glass plate (for example, Example 1 of Patent Document 1, Example 8 of Patent Document 2, Example 1 of Patent Document 3). In these examples, it is disclosed that good abrasion resistance and good water-repellant and oil-repellant characteristics were realized. Patent Document 4 discloses a perfluoropolyether group-containing silane compound having repellency to water and oil.